This article describes an affordable and setupfriendly cable-based localization technique for remotely operated vehicles (ROVs), which exploits the piecewise linear shape of the umbilical being equipped with a sliding ballast. Each stretched part of the cable is instrumented with a waterproof IMU to measure its orientation. Using cable's geometry, the vehicle's location can be calculated in relation to the other fixed or moving end of the cable. Experiments carried out with a robotic system in a water tank prove the reliability of this localization strategy. The study investigates the influence of measurement uncertainties on cable orientation and length, as well as the impact of the IMU location along the cable on localization precision. The accuracy of the localization method is discussed.